Any issue using a crank that's been ground -0.040 on mains and -0.020 on the rods? It came with .040 under bearings, so getting bearings isn't an issue. My concern is with strength. Block will be a .040 over 455 with 1382091 heads that have Stg1 valves, SpeedPro forged Pistons with a planned zero decked block, haven't decided on the cam yet, but nothing too crazy. Bought all this except the heads from a local machine shop going out of business(old guy retired)... customer never came back for his parts. Got a decent deal on it. Just questioning whether I should use the crank. I do have other cranks I could use, but would need to have them checked out or reground. Thoughts?
What your intentions on the build? Good street motor I wouldn't worry but check clearances for sure. Race motor I'd use a different crank.
With that build.. no worries on strength, the only issue is if you have any problem that would require a crank grind, then your going to have to use a fresh crank, and go thru the balance process again. Other than that, no big deal. JW
Mainly street motor, until the car goes to the GSNats. Lol like I said, nothing crazy...just a build to get into the 12s.
They cut far more off when they make stroker cranks out of stks......getting bearings of odd size can be hard
Yeah...I wasn't even questioning the rod journals being 20 under. It was the 40 under mains that caught my eye. I didn't even realize that you could go 40 under and have bearings available. I haven't seen any past 30 under. Heck, I just checked a few of the popular online sources for parts and couldn't find even a listing for 40 under mains. I just didn't know if going that small caused any weakness problems, even though it's only .005 per side smaller than the 30s. Thanks for the input, guys. Just allows me to put my mind at ease and not worry about it....and worry about other unimportant things. Lol
I could be wrong but I would thinknthe crank material in the mains would be just as thick as in the rods..........but maybe not..........though I don't see how not
They used to grind the 400 Chevy small block cranks 0.200 under on the mains, to make them fit the Chevy 350 blocks. That was the origin of the now-popular "383 stroker" SBC engines. "Two hundred under" is far more than the .040 you're dealing with. Any undersize that you can get bearings for is just fine. Strength is not really an issue provided they've retained sufficient radius at the journal edges. If the crank journals have no fillet, or too-small a fillet, though, that'd be a problem.
